The present invention relates generally to a system for managing electrical stresses in an X-ray tube for high voltage applications and, more specifically, to a cathode assembly with a high-voltage insulator that manages electrical stresses at its triple point.
X-ray systems are generally utilized in various applications for imaging in the medical and non-medical fields. For example, X-ray systems, such as radiographic systems, computed tomography (CT) systems, and tomosynthesis systems, are used to create internal images or views of a patient based on the attenuation of X-ray beams passing through the patient. Based on the X-ray beams, a profile of the patient is created. Alternatively, X-ray systems may also be utilized to in non-medical applications, such as detecting minute flaws in equipment or structures and/or scanning baggage at airports.
Typically, the X-ray system includes an X-ray tube that is utilized as the source of X-ray beams directed to a detector or film. The X-ray tube includes a cathode assembly and an anode assembly, which may be housed inside an evacuated tube. The cathode assembly includes a negative electrode and the anode assembly includes a positive electrode. The cathode assembly is typically heated to emit electrons, which travel across an open space, such as a vacuum, at very high speeds to collide with the positive electrode of the anode assembly, which produces the X-ray beams. As discussed above, these X-ray beams are utilized to generate the desired image.
The X-ray system may operate at high voltages and temperatures, which affect the life expectancy of the X-ray tube. For instance, a voltage of about 140 kilo-volts may be applied between the electrodes of the cathode assembly and anode assembly to facilitate emission and acceleration of electrons towards the anode. Further, the cathode assembly may include an insulator for electrical isolation and a cathode cup that focuses the electrons towards a particular location in the anode assembly. Each of these components, such as the insulator and the cathode cup may be operated at voltages of about 140 kilo-volts. Because of the high powers within the X-ray tube, some of the components within the X-ray tube may also be subjected to temperatures that exceed 200 degrees Celsius. As such, the temperatures and voltages involved with the operation of the X-ray tube may affect the life expectancy of the X-ray tube.
Because of the voltages and temperatures involved, various problems may occur that cause the X-ray tube to fail. The failures may include electrical stresses, such as high voltage instabilities, surface flashovers, and other insulating failures that reduce the life expectancy of the X-ray tube. That is, the insulator of the X-ray tube may fail because of the electrical stresses. As an example, the electrical stresses may cause a failure to initiate from a triple point or triple junction of the X-ray tubes. The triple point is a location where the material of the cathode, air (i.e. vacuum), and the material of the insulator join together. The electrical stresses from the high voltages and temperatures are severe at the triple point and can trigger flashovers that accelerate the aging of the insulator leading to its failure in the X-ray tube.
Thus, there exists a need for a new system for managing electrical stresses in X-ray tubes. In particular, there is a need for a new technique to overcome the electrical stresses at the triple point in X-ray tubes.